JP2019119422A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire which prevents local degradation of a reinforcement layer and can improve durability.SOLUTION: A pneumatic tire includes a laminate 1 that is formed of a film 2 of a thermoplastic elastomer composition containing a thermoplastic resin or a blend of the thermoplastic resin and an elastomer and a rubber composition 3 laminated on at least one side of the film 2, and at least one layer of a reinforcement layer 14 that is arranged adjacent to the laminate 1 and is formed of a steel cord, in which ends in a tire circumferential direction of the laminate 1 overlap each other at one portion on the tire circumference to form a lap-spliced part 4, and an interlayer rubber layer 3A formed of the rubber composition 3 is interposed between layers of the film 2 in the lap-spliced part 4, a lap length L in the tire circumferential direction of the laminate 1 in the lap-spliced part 4 satisfies expression (1).SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire, and more particularly, a laminate comprising a film of a thermoplastic elastomer composition comprising a thermoplastic resin or a blend of a thermoplastic resin and an elastomer and a rubber composition, and the laminate The present invention relates to a pneumatic tire provided with a reinforcing layer disposed adjacent to the tire, which makes it possible to prevent local deterioration of the reinforcing layer and to improve the durability.

  It has been proposed to use a film formed of a thermoplastic resin or a thermoplastic elastomer composition consisting of a thermoplastic resin and an elastomer as a tire component such as an inner liner layer. Such a film is subjected to a tire manufacturing process as a laminate in which a rubber composition for adhesion is laminated on at least one side, and a lap splice portion is formed by overlapping end portions of the laminate in the tire circumferential direction. (See, for example, Patent Documents 1 to 3).

  However, when the lap splice portion is formed by overlapping the end portions in the tire circumferential direction of the laminate as described above, a structure in which an interlayer rubber layer is interposed between layers of the film is formed in the lap splice portion. Air may permeate through such an interlayer rubber layer, and a slight air leak may occur. Although the area of the interlayer rubber layer occupied on the tire circumference is small, the influence on the whole pneumatic tire is small, but local deterioration occurs in the reinforcing layers such as the carcass layer and the belt layer due to the above-described air leak. There's a problem. In particular, heavy duty pneumatic tires for buses, trucks, etc. have a high air pressure, so when the above-mentioned film is used as an inner liner layer, air leakage tends to be large and local deterioration of the reinforcing layer is likely to occur. Become.

JP 2012-240658 A International Publication No. 2016/063785 International Publication No. 2016/2060128

  An object of the present invention is to provide a laminate comprising a film of a thermoplastic elastomer composition comprising a thermoplastic resin or a blend of a thermoplastic resin and an elastomer and a rubber composition, and to be disposed adjacent to the laminate In a pneumatic tire provided with a reinforcing layer, it is an object of the present invention to provide a pneumatic tire capable of preventing local deterioration of the reinforcing layer and improving the durability.

A pneumatic tire for achieving the above object comprises a film of a thermoplastic elastomer composition comprising a thermoplastic resin or a blend of a thermoplastic resin and an elastomer, and a rubber composition laminated on at least one side of the film. And at least one reinforcing layer disposed adjacent to the laminate and composed of a steel cord, and the end portions of the laminate in the tire circumferential direction are at least on the tire circumference. What is claimed is: 1. A pneumatic tire in which a lap splice portion is formed in one place and an interlayer rubber layer made of the rubber composition intervenes between layers of the film in the lap splice portion, the tire of the laminate in the lap splice portion. The wrap length L in the circumferential direction is characterized by satisfying the following formula (1).
L ≧ Gf × Pg × Gg / (Pf × Dc) (1)
However, Gf: average thickness [mm] of the film other than the lap splice portion
Gg: average thickness [mm] of the interlayer rubber layer at the lap splice portion
Pf: oxygen permeability coefficient of the film [10 ^-3 · mm · cc / (m ² · day · mmHg)]
Pg: oxygen permeability coefficient of the interlayer rubber layer [10 ^-3 · mm · cc / (m ² · day · mmHg)]
Dc: distance in the film thickness direction from the end of the film to the steel cord constituting the reinforcing layer [mm]

  The present inventors have found that a laminate comprising a film of a thermoplastic elastomer composition comprising a thermoplastic resin or a blend of a thermoplastic resin and an elastomer and a rubber composition, and a laminate disposed adjacent to the laminate, As a result of earnestly researching a pneumatic tire provided with a reinforcing layer composed of cords, the average thickness of each of the film and the interlayer rubber layer and the lap length necessary for preventing local deterioration of the reinforcing layer and The relational expression based on the oxygen permeability coefficient and the distance in the film thickness direction from the end of the film of the lap splice portion to the steel cord of the reinforcing layer has been derived, and the present invention has been achieved.

  In the present invention, a laminate comprising a film of a thermoplastic elastomer composition comprising a thermoplastic resin or a blend of a thermoplastic resin and an elastomer and a rubber composition laminated on at least one side of the film, and the laminate A lap splice is provided comprising: at least one reinforcing layer disposed adjacent to the laminate and composed of steel cords; the end portions in the tire circumferential direction of the laminate are overlapped at at least one point on the tire circumference In a pneumatic tire in which an interlayer rubber layer composed of a rubber composition is interposed between layers of a film in the lap splice portion, the lap length L of the laminate in the lap splice portion in the tire circumferential direction is the above formula (1 By ensuring that the required lap length L in the tire circumferential direction at the lap splice portion of the laminate is satisfied. Since the to prevent local degradation of the reinforcing layer, it is possible to improve the durability. Therefore, even in a heavy load pneumatic tire for buses, trucks, etc., local deterioration of the reinforcing layer can be prevented, and durability can be effectively improved.

In the present invention, a film obtained by dividing the oxygen permeability coefficient Pf of a film [10 ^-3 · mm · cc / (m ² · day · mmHg)] by the average thickness Gf of the film other than the lap splice portion [mm] The oxygen permeability [10 ^-3 · cc / (m ² · day · mmHg)] and the maximum air pressure P [kPa] of the tire preferably satisfy the relationship of Pf / Gf 50000 50000 / P. When using the said film as an inner liner layer, sufficient air permeation prevention performance can be ensured and durability can be improved effectively.

In the present invention, the oxygen permeability coefficient Pf at a temperature of 23 ° C. and a humidity of 65% of the film is preferably 20 [10 ⁻³ · mm · cc / (m ² · day · mm Hg)] or less. This can suppress cost and weight increase.

  In the present invention, the average thickness Gf of the film other than the lap splice portion is preferably 0.03 mm to 0.50 mm. Thereby, the defect at the time of shaping | molding can be suppressed and the deterioration of uniformity can be prevented.

In the present invention, the oxygen permeability coefficient Pg at a temperature of 23 ° C. and a humidity of 65% of the interlayer rubber layer is preferably 2000 [10 ⁻³ · mm · cc / (m ² · day · mmHg) or less. Thereby, the deterioration of uniformity can be prevented.

  In the present invention, the average thickness Gg of the interlayer rubber layer in the lap splice portion is preferably 0.10 mm to 1.00 mm. Thereby, the defect at the time of shaping | molding can be suppressed and the deterioration of uniformity can be prevented.

  In the present invention, the reinforcing layer is preferably a carcass layer, and the film is preferably disposed on the tire inner surface side relative to the carcass layer. Thereby, the occurrence of cracks can be suppressed and the durability can be effectively improved.

In the present invention, the oxygen permeability coefficient [10 ^-3 · mm · cc / (m ² · day · mmHg)] of the film and the interlayer rubber layer is JIS K-7126-2 under the conditions of a temperature of 23 ° C and a humidity of 65%. It is measured in accordance with the (equal pressure method).

It is a partially broken perspective view showing an example of an embodiment of a pneumatic tire of the present invention, and explains the physical relationship in a tire of a lap splice part. It is a sectional view showing an example of an embodiment of a lap splice part in a layered product of a pneumatic tire of the present invention, and expanding and showing a part of tire equatorial section.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the attached drawings. FIG. 1 shows an example of an embodiment of the pneumatic tire of the present invention. FIG. 2 shows an example of an embodiment of a lap splice portion in a laminate of a pneumatic tire according to the present invention. In FIG. 1 and FIG. 2, a carcass layer is shown as an example of the reinforcement layer which comprises the pneumatic tire of this invention. In FIGS. 1 and 2, an arrow Tc indicates a tire circumferential direction, and an arrow Tw indicates a tire width direction.

  In the pneumatic tire illustrated in FIG. 1, sidewall portions 12 and bead portions 13 are provided so as to be connected to the left and right of the tread portion 11. Inside the tire, a carcass layer 14 (reinforcing layer), which is a skeleton of the tire, is provided so as to straddle between the left and right bead portions 13 in the tire width direction, and around the bead cores 16 disposed in each bead portion 13 The tire is folded from the inside to the outside. The carcass layer 14 is composed of a plurality of steel cords 14A extending in the tire radial direction. A two-layered belt layer 15 made of a steel cord is provided on the outer peripheral side of the carcass layer 14 corresponding to the tread portion 11. An inner liner layer 10 is disposed on the inner side of the carcass layer 14, and a lap splice portion 4 extends in the tire width direction. That is, the inner liner layer 10 is disposed closer to the tire inner surface than the carcass layer 14.

  In the pneumatic tire shown in FIG. 2, the laminate 1 is used as the inner liner layer 10, and the end portions of the laminate 1 in the tire circumferential direction are overlapped with each other at at least one place on the tire periphery to have a lap splice structure. doing. The laminated body 1 is comprised by the film 2 and the at least 2 layer structure of the rubber composition 3 laminated | stacked on the at least one side. The film 2 is a film of a thermoplastic elastomer composition comprising a thermoplastic resin or a blend of a thermoplastic resin and an elastomer. The rubber composition 3 laminated on the film 2 is vulcanized and adhered to the film 2. In the wrap splice portion 4, an interlayer rubber layer 3 </ b> A made of the rubber composition 3 is present between the layers of the film 2. In FIG. 2, the cross sections of the film 2 and the main body of the rubber composition 3 are drawn in a straight line for easy understanding.

  When a single film 2 is used when the laminate 1 is to be lap-spliced, both ends of the film 2 in the tire circumferential direction are lap-spliced via the rubber composition 3 to form an annular shape. Alternatively, when a plurality of films 2 are used, the ends in the tire circumferential direction of the respective films 2 are lap-spliced through the rubber composition 3 so that the respective films 2 are joined together to form an annular shape as a whole. It is formed as Further, as shown in FIG. 2, when the laminate 1 has a three-layer structure of the film 2 and the rubber composition 3 laminated on both sides thereof, the end portions of the laminate 1 in the tire circumferential direction are The bonding is a structure in which the films 2 overlap with each other through the rubber composition 3, and the rubber-rubber bonds by vulcanization, so the adhesion is large.

In the pneumatic tire, the wrap length L in the tire circumferential direction of the laminate 1 in the wrap splice portion 4 is configured to satisfy the following formula (1). In the following formula (1), Gf is the average thickness [mm] of the film 2 other than the wrap splice portion 4, Gg is the average thickness [mm] of the interlayer rubber layer 3A in the wrap splice portion 4, and Pf is The oxygen permeability coefficient of the film 2 is [10 ^-3 · mm · cc / (m ² · day · mmHg)], Pg is the oxygen permeability coefficient of the interlayer rubber layer 3A [10 ^-3 · mm · cc / (m ² · · day · mmHg), and Dc is the distance [mm] in the film thickness direction from the end of film 2 to the steel cord (steel cord 14A in FIG. 2) constituting the reinforcing layer (carcass layer 14 in FIG. 2) It is.
L ≧ Gf × Pg × Gg / (Pf × Dc) (1)

  The above equation (1) indicates that the wrap length L needs to be longer as the average thickness becomes thicker in the interlayer rubber layer 3A or oxygen is more easily transmitted (as Pg or Gg becomes larger). On the other hand, if oxygen is more likely to permeate at a site other than the wrap splice portion 4 of the film 2 (if Pf / Gf indicating the oxygen permeability as described later increases), the oxygen permeated through the interlayer rubber layer 3A decreases. Since there is a tendency, the lap length L can be shortened, and if the distance Dc in the film thickness direction from the end of the film 2 to the steel cord 14A constituting the carcass layer 14 increases, the distance to the carcass layer 14 is increased. It shows that the wrap length L can be shortened because the influence is reduced. In addition, the lap | wrap length L measures the length of the tire circumferential direction from the front-end | tip of the one edge part of the film 2 to the front-end | tip of the other edge part. The average thickness Gf of the film 2, the average thickness Gg of the interlayer rubber layer 3A, the oxygen permeability coefficient Pf of the film 2, the oxygen permeability coefficient Pg of the interlayer rubber layer 3A and the end of the film 2 to the steel cord constituting the reinforcing layer The distance Dc in the film thickness direction is measured at the center position of the belt layer in the tire width direction.

  In the pneumatic tire described above, a film 2 of a thermoplastic elastomer composition comprising a thermoplastic resin or a blend of a thermoplastic resin and an elastomer and a rubber composition 3 laminated on at least one side of the film 2 And at least one reinforcing layer (carcass layer 14) disposed adjacent to the laminate 1 and made of steel cord, and the end portions of the laminate 1 in the tire circumferential direction are provided with each other. In a pneumatic tire in which an interlayer rubber layer 3A consisting of a rubber composition 3 is interposed between layers of a film 2 in a lap splice portion 4 by overlapping at least one point on the tire circumference to form a lap splice portion 4 When the wrap length L of the laminate 1 in the tire circumferential direction in the portion 4 satisfies the above-mentioned equation (1), the wrap sp Since lap minimum tire circumferential direction of the chair portion 4 length L is secured to prevent local degradation of the reinforcing layer, it is possible to improve the durability. Therefore, even in a heavy load pneumatic tire for buses, trucks, etc., local deterioration of the reinforcing layer can be prevented, and durability can be effectively improved.

  In the pneumatic tire, other tire constituent members (for example, in the area of 10 mm on both sides in the circumferential direction of the tire from the lap splice portion 4 including the lap splice portion 4) of the lap splice portion 4 of the laminate 1 (for example, It is preferable that there is no wrap splice portion in which the tire circumferential end portions of the carcass layer and the like are overlapped with each other.

  In the pneumatic tire, the average thickness Gf (see FIG. 2) of the film 2 other than the wrap splice portion 4 is preferably 0.03 mm to 0.50 mm. By appropriately setting the average thickness Gf of the film 2 as described above, it is possible to suppress a defect at the time of molding and to prevent deterioration of uniformity. Here, when the average thickness Gf of the film 2 is thinner than 0.03 mm, the film 2 tends to be wrinkled during molding, and conversely, when it is thicker than 0.50 mm, the uniformity tends to deteriorate.

In addition, it can be obtained by dividing the oxygen permeability coefficient Pf of the film 2 [10 ^-3 · mm · cc / (m ² · day · mmHg)] by the average thickness Gf of the film 2 except for the lap splice portion 4 [mm] It is preferable that the oxygen permeability [10 ^-3 · cc / (m ² · day · mmHg)] of the film 2 and the maximum air pressure P [kPa] of the tire satisfy the relationship of Pf / Gf 50000 50000 / P. As described above, by appropriately setting the oxygen permeability (Gf / Pf) of the film 2 with respect to the maximum air pressure P of the tire, sufficient air permeation prevention performance is secured when the film 2 is used as the inner liner layer 10 And the durability can be effectively improved. Here, when the oxygen permeability of the film 2 exceeds 50000 / P, when the film 2 is used as the inner liner layer 10, the air permeation prevention performance tends to be lowered, and the durability tends to be lowered.

In particular, the oxygen permeability coefficient Pf at a temperature of 23 ° C. and a humidity of 65% of the film 2 is preferably not more than 20 [10 ^-3 · mm · cc / (m ² · day · mmHg)]. It is preferable to set the lower limit to 0.5 [10 ^-3 mm cc / (m ² day mmHg)] or more. By appropriately setting the oxygen permeability coefficient Pf of the film 2 in this manner, the increase in cost and weight can be suppressed. Here, if the oxygen permeability coefficient Pf of the film 2 is larger than 20 [10 ^-3 · mm · cc / (m ² · day · mmHg)], it is necessary to thicken the thickness of the inner liner layer 10 (laminate 1) Leading to increased cost and weight. When the oxygen permeability coefficient Pf of the film 2 is smaller than 0.5 [10 ^-3 · mm · cc / (m ² · day · mmHg)], the durability is deteriorated, and a crack is easily generated.

  In the pneumatic tire, the average thickness Gg (see FIG. 2) of the interlayer rubber layer 3A in the wrap splice portion 4 is preferably 0.10 mm to 1.00 mm. By appropriately setting the average thickness Gg of the interlayer rubber layer 3A in this manner, it is possible to suppress a defect at the time of molding and to prevent deterioration of uniformity. Here, when the interlayer rubber layer 3A is thinner than 0.10 mm, the rubber composition 3 tends to be wrinkled during molding, and conversely, when it is thicker than 1.00 mm, the uniformity tends to be deteriorated.

The oxygen permeability coefficient Pg at a temperature of 23 ° C. and a humidity of 65% of the interlayer rubber layer 3A is preferably 2000 [10 ⁻³ · mm · cc / (m ² · day · mmHg) or less. The lower limit is preferably set to 50 [10 ^-3 mm cc / (m ² day mm Hg)] or more. By appropriately setting the oxygen permeability coefficient Pg of the interlayer rubber layer 3A as described above, deterioration of uniformity can be prevented. Here, if the oxygen permeability coefficient Pg of the interlayer rubber layer 3A is larger than 2000 [10 ^-3 · mm · cc / (m ² · day · mmHg)], the lap length L becomes excessively long, so the uniformity is deteriorated. Lead to If the oxygen permeability coefficient Pg of the interlayer rubber layer 3A is smaller than 50 [10 ^-3 mm cc / (m ² day mmHg)], the durability tends to be deteriorated.

  In the present invention, the film 2 is a film of a thermoplastic resin or a film of a thermoplastic elastomer composition comprising a blend of a thermoplastic resin and an elastomer.

  Examples of thermoplastic resins that can be used for the film 2 include polyamide resins [eg, nylon 6 (N 6), nylon 66 (N 66), nylon 46 (N 46), nylon 11 (N 11), nylon 12 (N 12) , Nylon 610 (N610), nylon 612 (N 612), nylon 6/66 copolymer (N6 / 66), nylon 6/66/610 copolymer (N6 / 66/610), nylon MXD6 (MXD6), nylon 6T, nylon 9T, nylon 6 / 6T copolymer, nylon 66 / PP copolymer, nylon 66 / PPS copolymer] and their N-alkoxyalkylated compounds [e.g., methoxymethylated nylon 6, nylon 6/6 Methoxymethylated copolymer of 610 copolymer, methoxymethylated compound of nylon 612, polyethylene Tellurium resin (eg, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), PET / PEI copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystalline polyester, Aromatic polyesters such as polyoxyalkylene diimido diacid / polybutylene terephthalate copolymers], polynitrile resins [eg, polyacrylonitrile (PAN), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), (meth) Acrylonitrile / styrene copolymer, (meth) acrylonitrile / styrene / butadiene copolymer], polymethacrylate resin [eg, polymethyl methacrylate (PMMA), polyethyl methacrylate], poly Nil-based resins [eg polyvinyl acetate, polyvinyl alcohol (PVA), vinyl alcohol / ethylene copolymer (EVOH), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, Vinylidene chloride / methyl acrylate copolymer, vinylidene chloride / acrylonitrile copolymer (ETFE)], cellulose resin [eg, cellulose acetate, cellulose acetate butyrate], fluorine resin [eg, polyvinylidene fluoride (PVDF), poly fluoride Vinyl (PVF), polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer], imide resin [eg, aromatic polyimide (PI)], etc. can be used.

  Among them, polyester resins and polyamide resins are preferable in terms of physical properties, processability, handleability and the like.

  In addition, a blend of a thermoplastic resin and an elastomer (a thermoplastic elastomer composition) capable of constituting the film 2 has a structure in which the elastomer is dispersed as a discontinuous phase in a matrix of the thermoplastic resin. By adopting such a structure, it is possible to obtain the same moldability as a thermoplastic resin. Among thermoplastic resins and elastomers constituting the thermoplastic elastomer composition, as the thermoplastic resin, those described above can be used. Examples of the elastomer constituting the thermoplastic elastomer composition include diene rubbers and hydrogenated products thereof [eg, natural rubber (NR), isoprene rubber (IR), epoxidized natural rubber, styrene butadiene rubber (SBR), butadiene Rubber (BR, high cis BR and low cis BR), nitrile rubber (NBR), hydrogenated NBR, hydrogenated SBR], olefin rubber [eg ethylene propylene rubber (EPDM, EPM), maleic acid modified ethylene propylene rubber ( M-EPM), butyl rubber (IIR), isobutylene and aromatic vinyl or diene monomer copolymer, acrylic rubber (ACM), ionomer], halogen-containing rubber [eg Br-IIR, CI-IIR, brominated isobutylene- p-methylstyrene copolymer (BIMS), chloroprene Rubber (CR), hydrin rubber (CHR), chlorosulfonated polyethylene rubber (CSM), chlorinated polyethylene rubber (CM), maleic acid-modified chlorinated polyethylene rubber (M-CM), silicone rubber [eg methyl vinyl silicone rubber , Dimethyl silicone rubber, methyl phenyl vinyl silicone rubber], sulfur-containing rubber [eg, polysulfide rubber], fluororubber [eg, vinylidene fluoride rubber, fluorine-containing vinyl ether rubber, tetrafluoroethylene-propylene rubber, fluorine-containing silicon rubber] Rubber, fluorine-containing phosphazene type rubber], thermoplastic elastomer [eg styrene type elastomer, olefin type elastomer, ester type elastomer, urethane type elastomer, polyamido type elastomer] etc. is preferably used Door can be.

  In particular, when blending a plurality of elastomers, it is preferred that 50% by weight or more of them is a halogenated butyl rubber, a brominated isobutylene paramethylstyrene copolymer rubber or a maleic anhydride modified ethylene alpha olefin copolymer rubber, It is preferable in that it can be increased to be flexible and durable from low temperature to high temperature.

  In addition, 50% by weight or more of the thermoplastic resin in the thermoplastic elastomer composition is nylon 11, nylon 12, nylon 6, nylon 66, nylon 6/66 copolymer, nylon 6/12 copolymer, nylon 6/12 Excellent durability can be obtained by being any of 10 copolymers, nylon 4/6 copolymer, nylon 6/66/12 copolymer, aromatic nylon, and ethylene / vinyl alcohol copolymer It is possible and preferable.

  When the thermoplastic elastomer composition is prepared by combining the specific thermoplastic resin and the elastomer described above, if the compatibility between the two is insufficient, the third component is compatibilized using a suitable compatibilizer. be able to. By mixing the compatibilizer with the blend system of the thermoplastic resin and the elastomer, the interfacial tension between the thermoplastic resin and the elastomer decreases, and as a result, the particle size of the elastomer forming the dispersed phase becomes finer. The characteristics of both components will be expressed more effectively. As such compatibilizer, generally, a copolymer having a structure of one or both of a thermoplastic resin and an elastomer, or an epoxy group, a carbonyl group, a halogen group or an amino group capable of reacting with the thermoplastic resin or elastomer. The structure of a copolymer having an oxazoline group, a hydroxyl group or the like can be taken. These may be selected according to the type of thermoplastic resin and elastomer to be blended, but among those commonly used, styrene / ethylene butylene block copolymer (SEBS) and its maleic acid modified product, EPDM, EPM, EPDM / styrene or EPDM / acrylonitrile graft copolymer and its maleic acid modified product, styrene / maleic acid copolymer, reactive phenoxy, etc. can be mentioned. The blending amount of the compatibilizer is not particularly limited, but preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the polymer component (the total of the thermoplastic resin and the elastomer).

  In the thermoplastic elastomer composition, the composition ratio of the thermoplastic resin to the elastomer is not particularly limited. For example, the composition ratio may be appropriately determined so that the elastomer has a structure dispersed as a discontinuous phase in the matrix of the thermoplastic resin. The composition ratio of the thermoplastic resin to the elastomer is preferably 90/10 to 20/80, more preferably 80/20 to 30/70, in terms of the weight ratio of thermoplastic resin / elastomer.

  In the present invention, a thermoplastic resin, or a thermoplastic elastomer composition obtained by blending a thermoplastic resin and an elastomer, is, for example, other than the above-mentioned compatibilizer within the range not impairing the properties necessary for constituting the film 2 Also, other polymers can be mixed. The purpose of mixing other polymers is to improve the molding processability of the material, to improve the heat resistance, to reduce the cost, etc. The materials used for this include, for example, polyethylene (PE), polypropylene ( PP), polystyrene (PS), ABS, SBS, polycarbonate (PC) etc. can be exemplified.

  In addition, fillers (such as calcium carbonate, titanium oxide and alumina), reinforcing agents such as carbon black and white carbon, softeners, plasticizers, processing aids, pigments, dyes, etc., which are generally incorporated into polymer formulations The inhibitor and the like can be optionally blended as long as the required properties of the film 2 are not impaired.

  Also, the elastomer blended with the thermoplastic resin can be dynamically vulcanized upon mixing with the thermoplastic resin. Vulcanizing agents, vulcanizing assistants, vulcanizing conditions (temperature, time) and the like in the case of dynamically vulcanizing may be suitably determined in accordance with the composition of the elastomer to be added, and are not particularly limited.

  The fact that the elastomer in the thermoplastic resin composition is dynamically vulcanized in this way means that the resulting thermoplastic elastomer composition contains the vulcanized elastomer, so that it is resistant to external deformation. There is a force (elasticity), and the effect of the present invention can be increased, which is preferable.

  As a vulcanizing agent, a general rubber vulcanizing agent (crosslinking agent) can be used. Specifically, examples of sulfur-based vulcanizing agents include powdered sulfur, precipitated sulfur, highly dispersible sulfur, surface-treated sulfur, insoluble sulfur, dimorpholine disulfide, alkylphenol disulfide, etc. An amount of 4 phr (herein, “phr” refers to parts by weight per 100 parts by weight of the elastomer component. The same applies hereinafter) can be used.

  Further, as the organic peroxide type vulcanizing agent, benzoyl peroxide, t-butyl hydroperoxide, 2,4-dichlorobenzoyl peroxide, 2,5-dimethyl-2,5-di (t-butyl peroxide) Examples include oxy) hexane, 2,5-dimethylhexane-2,5-di (peroxyl benzoate) and the like, and for example, about 1 to 20 phr can be used.

  Furthermore, as a phenol resin-based vulcanizing agent, a brominated compound of an alkyl phenol resin, a mixed crosslinking system containing a halogen donor such as tin chloride or chloroprene, and an alkyl phenol resin can be exemplified. Can.

  Other examples include zinc flower (about 5 phr), magnesium oxide (about 4 phr), liserge (about 10 to 20 phr), p-quinone dioxime, p-dibenzoyl quinone dioxime, tetrachloro-p-benzoquinone, poly-p- Examples include dinitrosobenzene (about 2 to 10 phr) and methylenedianiline (about 0.2 to 10 phr).

  In addition, if necessary, a vulcanization accelerator may be added. As the vulcanization accelerator, general vulcanization accelerators such as aldehyde / ammonia type, guanidine type, thiazole type, sulfenamide type, thiuram type, dithioate type, thiourea type, etc. About 2 phr can be used.

  The rubber material constituting the rubber composition 3 includes diene rubbers such as natural rubber, isoprene rubber, epoxidized natural rubber, styrene butadiene rubber, hydrogenated styrene butadiene rubber, ethylene propylene rubber, maleic acid modified ethylene propylene An olefin rubber such as rubber can be preferably used.

  And in order to improve the adhesiveness with the rubber composition 3 which adjoins the said film 2, it is good to interpose an adhesive layer and to laminate | stack it. As polymers constituting the adhesive layer, acrylate copolymers such as ultra high molecular weight polyethylene having a molecular weight of 1,000,000 or more, preferably 3,000,000 or more, an ethylene ethyl acrylate copolymer, an ethylene methyl acrylate resin, an ethylene acrylic acid copolymer and the like And its maleic anhydride adduct, polypropylene and its maleic acid modified product, ethylene propylene copolymer and its maleic acid modified product, polybutadiene resin and its maleic anhydride modified product, styrene-butadiene-styrene copolymer, styrene Ethylene-butadiene-styrene copolymer, fluorine-based thermoplastic resin, polyester-based thermoplastic resin, etc. are preferably used.

  Although the embodiment described above describes a pneumatic tire in which the reinforcing layer is the carcass layer 14, the present invention can also be applied to a pneumatic tire in which the reinforcing layer is a belt layer or a side reinforcing layer. In particular, when the reinforcing layer is the carcass layer 14 and the film 2 constituting the laminate 1 is disposed closer to the inner surface of the tire than the carcass layer 14, generation of cracks is suppressed and durability is effectively achieved. Can be improved.

  A film of thermoplastic elastomer composition comprising a blend of a thermoplastic resin and an elastomer, and a rubber laminated on both sides of the film, with a tire size of 195 / 65R15 (for passenger car) and 275 / 70R22.5 (for heavy load) A laminate comprising the composition and a single reinforcing layer disposed adjacent to the laminate and comprising a steel cord, and the circumferential portions of the laminate in the circumferential direction are overlapped to form a lap splice. In a pneumatic tire in which an interlayer rubber layer consisting of a rubber composition is interposed between layers of the film in the lap splice portion, the type of tire, the lap length L, the average thickness Gf of the film, the oxygen permeation of the film Coefficient Pf, average thickness Gg of interlayer rubber layer, oxygen permeability coefficient Pg of interlayer rubber layer, steel cord of reinforcing layer from end of film Until the film thickness direction of the distance Dc, to prepare a tire Gf × Pg × Gg / compare (Pf × Dc) was varied as shown in Table 1. Examples 1-3 and Examples 1-5.

  In addition, in each test tire, it was made common that the reinforcement layer arrange | positioned adjacent to a laminated body is a carcass layer. In the tire of Comparative Examples 1 and 3 and Example 3 (oxygen permeability coefficient Pf = 10 in Table 1), the films were nylon 6/66 copolymer (N6 / 66) and brominated isobutylene-p-methyl. It is a thermoplastic elastomer composition containing a styrene copolymer (BIMS) at a weight ratio of 50/50, and in a tire of Comparative Example 2 and Examples 1 and 5 (oxygen permeability coefficient Pf = 5 in Table 1), a film Is a thermoplastic elastomer composition comprising N6 / 66 and BIMS in a weight ratio 75/25, and in the tire of Example 2, 4 (oxygen permeability coefficient Pf = 20 of Table 1), the film is N6 / 66 and BIMS And a weight ratio of 30/70. In each test tire, the rubber composition was in common that it is a rubber composition containing natural rubber and styrene butadiene rubber as main components.

  The durability of each of these test tires was evaluated by the following test method, and the results are also shown in Table 1.

durability:
Each test tire is assembled to either rim size 15 × 6 JJ (for passenger car) or rim size 22.5 × 7.50 (for heavy load), so that the tire internal pressure is 240 kPa (for passenger car) or 900 kPa (for heavy load) Was filled. The tire was subjected to an indoor drum test machine and loaded at 120% of the maximum load capacity specified by JATMA, and traveled 20,000 km at a speed of 80 km / h (for passenger car) or 50 km / h (for heavy load). Thereafter, the steel cord constituting the reinforcing layer was visually observed to confirm the occurrence of separation, and when it occurred, the length of separation [mm] was measured.

  As can be seen from Table 1, in the tires of Examples 1 to 5, the lap length L of the laminate in the tire circumferential direction was set to be equal to or greater than the length obtained from the equation (1) defined in the present invention. The occurrence of separation in the steel cord constituting the reinforcing layer can be prevented, and the durability is improved as compared with the tires of Comparative Examples 1 to 3.

Reference Signs List 1 laminated body 2 film 3 rubber composition 3A interlayer rubber layer 4 lap splice portion 10 inner liner layer 11 tread portion 12 sidewall portion 13 bead portion 14 carcass layer 14A steel cord 15 belt layer 16 bead core L wrap length

Claims (7)

A laminate comprising a film of a thermoplastic elastomer composition comprising a thermoplastic resin or a blend of a thermoplastic resin and an elastomer, and a rubber composition laminated on at least one side of the film, and adjacent to the laminate And at least one reinforcing layer composed of a steel cord, and the circumferential portions of the laminate in the tire circumferential direction are overlapped at at least one place on the tire circumferential surface to form a lap splice portion. In a pneumatic tire in which an interlayer rubber layer made of the rubber composition intervenes between layers of the film in the lap splice portion, a lap length L of the laminate in the lap splice portion in the tire circumferential direction is represented by the following formula (1 A pneumatic tire characterized by satisfying.
L ≧ Gf × Pg × Gg / (Pf × Dc) (1)
However, Gf: average thickness [mm] of the film other than the lap splice portion
Gg: average thickness [mm] of the interlayer rubber layer at the lap splice portion
Pf: oxygen permeability coefficient of the film [10 ^-3 · mm · cc / (m ² · day · mmHg)]
Pg: oxygen permeability coefficient of the interlayer rubber layer [10 ^-3 · mm · cc / (m ² · day · mmHg)]
Dc: distance in the film thickness direction from the end of the film to the steel cord constituting the reinforcing layer [mm] The film obtained by dividing the oxygen permeability coefficient Pf of the film [10 ^-3 · mm · cc / (m ² · day · mmHg)] by the average thickness Gf of the film other than the lap splice portion [mm] Oxygen permeability [10 ^-3 · cc / (m ² · day · mmHg)] of the tire and the maximum air pressure P [kPa] of the tire satisfy the relationship of Pf / Gf / 50000 / P The pneumatic tire according to 1. The oxygen permeation coefficient Pf at a temperature of 23 ° C. and a humidity of 65% of the film is 20 [10 ⁻³ · mm · cc / (m ² · day · mm Hg)] or less. Pneumatic tire.   The pneumatic tire according to any one of claims 1 to 3, wherein an average thickness Gf of the film other than the wrap splice portion is 0.03 mm to 0.50 mm. The oxygen permeability coefficient Pg at a temperature of 23 ° C. and a humidity of 65% of the interlayer rubber layer is 2000 [10 ^-3 · mm · cc / (m ² · day · mm Hg)] or less. The pneumatic tire according to any one of the above.   The pneumatic tire according to any one of claims 1 to 5, wherein an average thickness Gg of the interlayer rubber layer in the lap splice portion is 0.10 mm to 1.00 mm.   The pneumatic tire according to any one of claims 1 to 6, wherein the reinforcing layer is a carcass layer, and the film is disposed closer to the tire inner surface than the carcass layer.

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